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Authentication

Email Authentication

Technical methods (SPF, DKIM, DMARC) that verify the sender's identity and prevent email spoofing.

Definition

Email authentication encompasses technical protocols that verify the identity of email senders. The main methods are SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance). Together, these protocols prove that emails genuinely come from your domain and have not been forged or modified in transit.

Why It Matters

Email authentication is now required for reliable inbox delivery. Gmail and Yahoo require SPF, DKIM, and DMARC for bulk senders. Without authentication, your emails may be rejected or marked as spam. Authentication also protects your brand from phishing attacks that impersonate your domain.

How It Works

SPF lists authorized sending IPs in your DNS records. DKIM adds a cryptographic signature that proves the email was authorized by your domain. DMARC ties them together, telling receivers how to handle authentication failures. Receiving servers check these records and use the results in spam filtering decisions.

Best Practices

  • 1Implement all three: SPF, DKIM, and DMARC
  • 2Start DMARC with p=none to monitor before enforcing
  • 3Include all legitimate sending sources in your SPF record
  • 4Use 2048-bit keys for DKIM signatures
  • 5Monitor DMARC reports to catch authentication issues

Automatic Email Authentication

Sequenzy automatically configures SPF, DKIM, and DMARC for your sending domains with guided DNS setup.

Learn More

Frequently Asked Questions

All three work together, but if prioritizing: DKIM provides the strongest authentication, SPF is easiest to implement, and DMARC enforces the policy. Gmail and Yahoo now require all three for bulk senders.

Technically yes, but your emails will likely go to spam or be rejected. Major providers now require authentication. Even small senders benefit from proper setup to avoid deliverability issues.